Protection from Predators

Cats
Nesting birds are extremely vulnerable to cats, as are fledglings and birds roosting for the night. Bell collars on cats offer birds little protection. Nailing a sheet metal guard or cone to a tree trunk is unsightly, but may deter less agile felines. Houses mounted on metal poles are the most difficult for predators to reach, especially if you smear the poles with a petroleum jelly and hot pepper mixture. The best deterrent is for owners to keep their cats inside whenever possible.

Dogs
Pet dogs are a hazard to nestlings in the spring and summer. Don't let your dog run loose during nesting time.

Squirrels
Red squirrels, and sometimes gray squirrels, can become a serious menace to bird houses and the birds themselves. If you find your riest hole enlarged, chances are a red squirrel is the culprit. Once inside the box, squirrels make a meal of the eggs and young. Adding a predator guard made of sheet metal to the entrance hole is usually enough to keep squirrels out.

Raccoons and Opossums
Raccoons and opossums will stick their arms inside nest boxes and try to pull out the adult, young, and eggs. Adding a '/.,-inch thick predator guard to the bird house or an inverted cone to its pole support is a simple solution.

Snakes
Snakes play an important part in the balance of nature. If you find one in your bird house, don't kill it. Snake-proof your house by putting it on a metal pole lathered with petroleum jelly or red cayenne pepper.

Insects
Many insects lay their eggs and pupate in bird houses. Inspect your bird houses for signs of gypsy moths, blow flies, wasps, ants, gnats and bees. Keep bees and wasps from attaching their nests by coating the inside of the roof with bar soap. In areas where gypsy moths abound, avoid placing boxes in oak trees, which the gypsy moths favor.